The present invention relates to gas turbine engines and, more particularly, to apparatus for detecting excess leakage of liquids from within a gas turbine engine.
Commercial gas turbine or turbofan engines such as, for example, the type CFM56-5C2 manufactured by General Electric Company, include an extensive liquid drain system for disposing of internally developed leakage liquids and vapors to an area outside the engine, nacelle and pylon cavities. An exemplary system includes drain lines connected to each of a plurality of liquid sources. Typically these sources are located at oil, hydraulic or fuel seal points adjacent to moving elements. For example, one of the sources is located adjacent to the gearbox in the engine where other components are coupled to the engine via shafts passing through the gearbox housing. Other sources are located around hydraulic actuators and fuel driven valves. The drain lines in the aforementioned engine each lead to a drain mast assembly attached to the engine nacelle and arranged to vent the draining liquids outside the nacelle slip stream boundary layer. These drain systems provide an indication of leakage from a source to which the drain is connected but no indication of the quantity or leakage rate of that source. In most commercial engine applications, operational drains drain away liquids that might accumulate during operation and service drains collect liquids for removal during maintenance servicing. Leakage associated with such service drains can be determined during maintenance servicing by measuring the quantity of liquid collected.
A conventional drain mast assembly appears as an air foil shape extending from an outer surface of a nacelle or other engine fairing. The various drain lines feed into the drain mast assembly which then vents the leakage liquid to the atmosphere outside the slip stream boundary layer of the nacelle. Because there are many drain lines connected to the drain mast assembly, it is difficult to determine which particular drain line is leaking liquid because the liquids tend to run onto adjacent drain line openings depending on the attitude of the drain mast and the aerodynamic pressure field on the nacelle. This disadvantage of existing systems creates a problem for troubleshooting a leaking drain and requires an investigation inside the nacelle and cowl assembly, which is a time consuming task.